Such a long thread, I even don't know wether I posted sometimes or not.
For me it's easy, I like 4 person parties and I hope it stays as it is. I don't care at all for tabletop here because there usually a char is played by a person, but in the video game you have to play all the party members. I find it utterly annoying to do so in Pathfinder turn based for example. As BG 3 (thankfully) is turn-based-only, a party bigger that 4 is a nightmare for me. Ok, I'm exaggerating. It wouldn't be as bad as in Pathfinder with it's stupid 3.5e or so rules, but bad enough.